Worms don’t always result in death, and infections tend to be chronic in nature. If you have a large free ranging flock, chances are that you may not notice the few that are experiencing problems as a result. Weight loss, malnutrition, and depression are typical symptoms of worm infections in general.
Free-ranging birds enjoy many benefits and privileges over those kept in coops and cages. However, there can be a host of problems that occur with the free-range flock that aren’t necessarily problems for the ‘coopers’.
Coccidiosis is an obvious potential problem, although cocci outbreaks have been known to occur inside of a secured coop as well. There’s also predation, the possible consumption of poisonous plants, and the accidental poisoning from the use of typical yard and garden products such as Diazinon. (Never use Diazinon within 75 feet of a pond either – you can actually be fined by the EPA.) Probably the most under diagnosed problem though is an infestation of WORMS.
The most common worms that effect poultry are called nematodes, or roundworms. And the most common of the nematodes are known as ascarids. Ascaridia galli can affect chickens, turkeys, doves, ducks, and geese. These worms are usually found in the intestine, but can appear in the esophagus, crop, gizzard, oviduct, or body cavity. The typical symptom is unexplainable weight loss. A severe infestation can also cause an intestinal obstruction and result in death. Sometimes a bird will contract both an ascarid and a cocci infection at the same time, and because of the synergistic relationship between the two, will succumb more readily than if they were only stricken with one infection or the other. In rare but documented cases, an ascarid can actually find its way into a hen’s egg, which can be quite unappealing to an unsuspecting fresh egg customer. The worm can be detected by candling.
One of the most difficult worm infections to diagnose though is Capillaria, due to its extremely small size. Many times they go completely unseen during necropsy, only to be found later through microscopic examination.
A common nematode of the respiratory tract is known as the gapeworm, or Syngamus trachea. Many types of game birds, especially pheasants, as well as turkeys and chickens can be affected.
Birds with gapeworm infestation show signs of respiratory distress due to both the damage to the lungs and to the trachea that is caused by the worms. Young birds and bantams are especially vulnerable due to their relatively small trachea. Symptoms include depression, gasping for breath, and head shaking in an attempt to remove the worms from the trachea. Tracheal rales (a gurgling sound made during breathing that accompanies tracheal irritation) can be heard in many cases, and can sometimes be mistaken for an upper respiratory infection of some other cause.
The most commonly known worm ‘hosts’ (carriers) are the earthworm, cockroach, beetle, sowbug, grasshopper, and earwig. The earthworm is known specifically to carry the gapeworm.
In the case of the gapeworm, once a susceptible bird ingests an infested earthworm, the larvae penetrate the wall of the intestine and eventually end up in the lungs. Once in the lung, the larvae migrate into the bronchi. A molt of the larvae takes place resulting in the adult gapeworm, and the adult worms migrate up the respiratory tree to the trachea where the male and female worms intertwine and attach themselves to each other permanently. The entire process from the time the bird ingests the earthworm to the time adult gapeworms can be found in the trachea is approximately 7 days.
Gapeworm egg production begins about 14 days after infestation of the larvae. The eggs are then coughed up into the mouth of the bird and passed out into the feces. In the droppings, the eggs incubate for 8 to 14 days under optimum conditions of temperature and moisture to become infective larvae, thus completing the life cycle.
Under necropsy, the adult gapeworms appear as long, red strands attached to the tracheal wall, almost like thin strands of blood. In chronic infestations, nodules of inflammatory tissue appear in the tracheal wall at the site of worm attachment. You can imagine how difficult it would be to breathe normally under these conditions.
There are ways to control or reduce the infestation of your free ranging birds by worms. The obvious one is to worm on a regular basis. I use wormers with caution and usually only worm in the spring and fall, and also before breeding. I also worm any new birds that I bring into my flock during their period of quarantine. I prefer Ivermectin but there are many good wormers out there such as Piperazine and Levamisole (used according to recommended dosages).
Another way is to control the birds’ environment to reduce the number of infective larvae. You can accomplish this by tilling confinement dirt pens at the end of the growing season to expose larvae and eggs to the elements and dilute them with fresh earth. You can also use a soil nematode control chemical to reduce the earthworm population in the pasture areas, but I would consult a professional turf management company for the recommended product and the amount of time you would have to keep your birds off of the pasture before they could safely return to forage.
If you provide your free ranging flock with an indoor pen in the evening for roosting, then changing the litter once a week will break the 8 to 14 day cycle needed for eggs to incubate into infective larvae. This practice can even be effective for coop raised birds since although indoors, they still have the potential of ingesting a carrier.